Atoms make quantum coprocessor

January 14/21, 2004

Researchers from Brussels Free University
in Belgium (ULB) and the Niels Bohr Institute in Denmark have shown that
the collective spin of clouds of atoms can be used to compute.

Atomic particles like atoms, electrons and photons have spin states
that can be likened to the two poles of a magnet and can be used to represent
the 1s and 0s of digital information. In addition, the weird quantum traits
of superposition and entanglement make it possible to carry out many calculations
at once on a series of spin states, making quantum computers potentially
very powerful.

The trick is controlling and reading such states. This is easier
using a cloud of atoms rather than a single atom or particle.

The researchers' previously proved that clouds of atoms could
be entangled. Their new scheme theoretically generates a cloud of atoms
whose collective spin points in two slightly different directions at once;
this spin is relatively long-lived, making for plenty of time to carry
out computations.

Most quantum computing schemes call for manipulating the quantum
states of individual particles; there are several schemes, however, that
could use atom clouds instead.

The researchers' method could also be used to strengthen the entanglement
between distant entangled atom clouds used for quantum communications,
according to the researchers.

The method could be ready for practical use within a decade, according
to the researchers. The work appeared in the August 8, 2003 issue of Physical
Review Letters.